In 1947 Moore of the Department of Surgery, University of Minnesota, found that fluorescein injected intravenously into patients has the property of elective localization in malignant tissues.
Five cubic centimeters of a 20 per cent sodium fluorescein solution was injected intravenously from three to eight hours before a planned laparotomy for gastric carcinoma At the operation the suspected lesions were inspected with an ultraviolet lamp. Differences between normal and malignant tissues were then noted, the malignant tissues fluorescing with a vivid yellow color. The main exceptions were in cases in which the malignant tissues were situated more than a few millimeters below the surface. In these cases, little or no fluorescence was noted, presumably because ultraviolet light can penetrate only a few millimeters through surrounding tissues. In 11 of 17 cases of of malignant tumors of the gastrointestinal tract a high grade fluorescence was associated with verified diagnoses of malignancy